Tom Bartlett produced Zipcycle from 1993-2003.
Using a belt reduction Friction drive powered by a Homelite 25cc String Trimmer.
"Most bikes would run from 23-25 mph. We experimented with different gearing and found that although we could run a higher gear and obtain slightly higher...

The RYOBI 30cc 4 CYCLE has an external belt/pulleys for the OHC.
If the friction roller could be mounted on the pulley, it could be 4 times larger.
Many Walmart 20" trick bikes have 2.3" wide street tires
that would give a lot of contact area for small rollers.
The last one I bought...

This is Scotto's 12hp, CVT, over 60mph:
212cc Predator Ride......terrorizing the neighborhood (in California)
https://www.youtube.com/watch?v=V2aFd3x7Vms
At 11:44, you can see his speedometer is just a hair under 50 mph.
The worse case would be the piece of steel that would shred your...

Scotto has 2 lbs CST Cyclops Tires (24" x 2.4") on his 20hp 212cc racer.
A 22" x 2.5" moped tire has weight of 4.6 lbs (IRC NR2 2.50-18), Rated for about 70 mph.
Much of the added weight is in the sidewalls.

The BMX guys mentioned 2 headset models that clear the 1.125 steerer tube.
2 minutes with $10 HF air die grinder is much better, Thanks.
Schwinn had some of the best chrome, easy clean up for re-sale.
I would hold on to the Rear wheel. Shelden claims they built some
of the strongest...

It used to be, fill out a form, most using the S/N of bike, pay $20 one time fee.
Mail it in, No inspection. All states seem to be tightening up.
Plenty of videos of Scotto riding on the street.
The other MAB forum may have info.

All Santana Road Tandems $3k - $11k come with rim brakes on the front wheel because of better raw stopping power.
The Rear wheel normaly can only use 25% of the stopping power of the front before skidding, Santana will gladly sell you a Disk for it.

The engineers at Santana Tandems:
"Unless bike discs become 3x more powerful (which won’t happen) the best answer for the front of a road tandem will continue to be a long-armed (higher leverage) V-brake. "
http://santanatandems.com/Techno/UnderstandingBraking.html

Hi Tony,
Yes, very good deal for their condition. Portland has a great market for vintage Schwinn.
Schwinn made some HeavyWeights that looked the same as Cantalever MiddleWeights except for wider tire clearances and rims, that allow many more tire options:
(More standard rim diameter)...

Hi Ultralight01
The first CL bike looks like the fork crown and cranks are wrong.
The second is a newer China bike, that has the larger down and top tubes.
This is what your are looking for:
Schwinn Middleweight - $100 (Oak Grove)
http://portland.craigslist.org/clc/bik/5893033929.html
and...

The Suntour freewheel is 30 years old, not going to do 7 speed SIS index shifting.
(Cogs and spacers too wide). But quality is as good as Shimano.
LBS trash many 7 speed wheels. Cheaper to replace than labor to fix.
Chop off outer 3 cogs and weld it up. Free wheeling function not required...